This application claims the benefit of Japanese Application No. 2000-175949, filed Jun. 12, 2000 in the Japanese Patent Office, the disclosure of which is incorporated herein by reference.
1. Field of the Invention
The present invention generally relates to a method of controlling the rotational rate of an optical disc in an optical disc recording device, and more particularly, to an optical disc recording device that records data by determining a constant rotational rate for the optical disc.
2. Description of the Related Art
At present, recordable optical discs (i.e., compact disc recordable media (CD-R), or compact disc rewritable media (CD-RW)) are widely used as recording media for preserving data in personal computers, or the like. An optical disc reading and recording device records data to an optical disc using one of two well-known methods. One is a constant linear velocity (CLV) recording method, in which data are recorded by securing a constant linear velocity of an optical disc. The other is a constant angular velocity (CAV) recording method, in which data are recorded by securing a constant rotational rate (i.e., number of rotations, spin rate) of an optical disc.
Generally, the optical disc has a memory region that includes a plurality of recording tracks having a concentric circular or spiral shape. The CD-R or CD-RW needs to record data by securing a constant recording density in recording regions for each circumferential area of the optical disc. Thus, for the CAV recording method that uses a constant rotational rate, the recording capacity for the recording regions on the outer circumference is greater than for the recording regions on the inner circumference. In other words, data recorded on the optical disc per unit time volume (i.e., a recorded data rate) using the CAV recording method is greater at the outer circumference of the optical disc than at the inner circumference of the optical disc. By using the CAV recording method, the data is recorded in the recording regions of the entire circumference without varying the rotational rate of the optical disc, which is advantageous in more easily controlling the motor when randomly recording the data in the recording regions.
FIG. 4 shows a waveform for a known process for controlling the rotational rate of an optical disc.
The horizontal axis represents positions in the recording regions for respective circumferences of the optical disc along the radial direction. The longitudinal axis shows recorded data rates. As shown, P1 is the location of the innermost circumference of the optical disc, and P2 is the position of the outermost circumference of the optical disc. The recorded data rate of the innermost circumference is Tmin, which is the minimum recorded data rate for the optical disc, while the recorded data of the outermost circumference is Tmax, which is the maximum recorded data for the optical disc. W1 is the waveform representing the recorded data rates corresponding to the recording regions of the respective circumferences between P1 and P2.
According to the known method of controlling the rotational rate of the optical disc, the rotational rate is determined so that the recorded data rate of the outermost circumference of the optical disc (P2) is the maximum value Tmax, as shown in the waveform W1 of the FIG. 4.
For example, based on the Hi-Speed standard, the recorded data rates with respect to the all of the circumferences are in the range of 600 kb/s to 1500 kb/s. Based on these values, the recorded data rate of the optical disc outermost circumference is the maximum, 1500 kb/s, which is used to determine the rotational rate during the data recording. As such, the rotational rate is predetermined based on the outermost radius of the optical disc. Therefore, conventionally, the rotational rate for the optical disc recording device is determined in accordance with the size of the optical disc within it.
The known method of controlling the rotational rate of the optical disc using the size and shape of the optical disc has the following problems.
For an optical disc, such as the CD-RW disc based on the Hi-Speed standard, since the rotational rate is determined to be the maximum recorded data rate at the outermost circumference, the recorded data rate is less for all of the other circumferences of the optical disc, regardless of where they are located on the optical disc. Therefore, if the optical disc is formatted to record data in some specific recording regions, and in particular in recording regions near the inner circumference, the recorded data rate is dramatically lower than the maximum recorded data rate. This result occurs despite the fact that the whole optical disc is capable of receiving data recorded at the maximum recorded data rate.
For example, as shown in FIG. 4, if the rotational rate of the optical disc is determined so that the recorded data rate of the outermost circumference of the optical disc is the maximum recorded data rate, the recorded data rate for the recording region P3 becomes Tc, and the recorded data rate for the recording region P4 is Tb. Both recorded data rates Tc and Tb are dramatically less than the maximum recorded data rate Tmax for the optical disc. As a result, the performance of the optical disc cannot be efficiently used.
It is, therefore, an object of the present invention to provide a method of controlling the rotational rate of an optical disc, and an optical disc recording device using this method to more efficiently use the performance of the optical disc.
Additional objects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.
To achieve the above and other objects, according to an embodiment of the present invention, there is provided a method of determining a constant rotational rate of an optical disc in an optical disc recording device that includes varying the rotational rate according to a positions of the farthest recording regions from a center of the optical disc.
According to another embodiment of the present invention, the method further comprises reading a farthest position information representing the positions of the farthest recording region, and calculating a distance from the center of the optical disc to the farthest recording region based on the read position information.
According to a still further embodiment of the present invention, the method further comprises calculating the rotational rate so that the recorded data rate of the farthest recording region can be the maximum value for the optical disc based on the distance of the farthest recording region from the center of the optical disc.
According to another embodiment of the present invention, the recording region is a region of the optical disc formatted to record the data.
According to yet another embodiment of the present invention, the farthest position information is an address value corresponding to the farthest circumference formatted to be recorded upon on the optical disc.
According to yet a further embodiment of the present invention, there is provided an optical disc recording device for recording the data on the recording regions of the optical disc by securing a constant rotational rate for the optical disc that comprises a reading unit to read a farthest position information for a farthest recording region that is farthest from a center of the optical disc, a first calculating unit to calculate both a distance from the center of the optical disc to the farthest recording region, and a second calculating unit to calculate a rotational rate so that the recorded data rate of the farthest recording region is the maximum recorded data rate for the optical disc based on the calculated distance.
According to an aspect of the invention, a computer readable medium is encoded with processing instructions for implementing a method of determining a rotational rate of a disc having recording regions performed by a computer, where the method includes sensing data on the disc; and determining the rotational rate for the disc based upon a maximum recorded data rate for the disc and the sensed data.